Researchers simulate the earthquake on walls that mimic what’s found in turn-of-the-century row houses

“There’s very little information on the seismic behavior of unreinforced masonry construction in eastern North America and no validated numerical tools for structural engineers to use to analyze the brownstones.”

BUFFALO, N.Y. – A brick wall imitating part of a New York
City row house (often called a “brownstone”) suffered
minor damage but remained intact during a simulation of the 2011
Virginia earthquake, according to a preliminary analysis of tests
conducted Feb. 19 at the University at Buffalo.

The tests — a rarity given the perceived low risk of East
Coast seismic activity — will be used to validate numerical
models that will help estimate potential human casualties, property
losses and business interruption costs, said Andrew Whittaker,
director of MCEER, the university’s research center for
earthquake engineering and extreme events.

“There’s very little information on the seismic
behavior of unreinforced masonry construction in eastern North
America and no validated numerical tools for structural engineers
to use to analyze the brownstones,” said Whittaker, also
professor and chair of UB’s Department of Civil, Structural
and Environmental Engineering.

The lack of information is a problem because earthquakes, as
evidenced by the Virginia quake and a 5.5 magnitude temblor that
struck the New York City area in 1884, do occur, Whittaker
said.

Large cities pose significant risks because of high population
density and aging infrastructure. For example, a 2002 study by the
New York City Area Consortium of Earthquake Loss Mitigation (NYCEM)
found that unreinforced masonry buildings account for nearly 80
percent of the city’s housing stock.

To conduct the tests, researchers built two 14-foot walls using
materials such as 100-year-old brick designed to imitate existing
buildings. One wall was typical of New York City buildings while
the other (common on the West Coast) was reinforced with steel rods
and bolts that positively connected the flooring to the wall.

Using data from the U.S. Geological Survey, they programmed an
earthquake shake table to mimic ground accelerations observed
during the 5.8 magnitude Virginia quake. Both walls moved but held
together.

A second series of tests mimicking ground accelerations from a
6.3 magnitude quake in Christchurch, New Zealand, in 2011 produced
a very different result. The parapet on the unreinforced wall
collapsed, whereas the reinforced wall suffered some damage but
remained standing.

“The data that we obtain from these tests is going to be
used to develop and improve numerical models of these buildings to
determine how vulnerable these buildings can be in
earthquakes,” said Gilberto Mosqueda, a UB research professor
and associate professor in structural engineering at the University
of California, San Diego.

The tests were conducted in collaboration with the Structural
Engineers Association of New York, the International Masonry
Institute, International Union of Brick Layers & Allied Craft
Workers – Local #3 NY, United Materials LLC, Scranton's
Thruway Builders Supplies, and Reclaim Syracuse Inc.

A more detailed analysis of the results will be published in an
MCEER report later this year and in peer-reviewed journals. MCEER
is planning additional tests of unreinforced masonry buildings.

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